Transflective liquid crystal display device having a color filter and method for fabricating thereof

ABSTRACT

A color filter substrate for a liquid crystal display device includes a base substrate having a transmissive portion and a reflective portion. The transmissive portion has a groove, a color filter layer on the substrate, and a black matrix on the color filter layer.

CROSS REFERENCE

This application is a Divisional of application Ser. No. 11/882,862filed on Aug. 6, 2007, now U.S. Pat. No. 7,697,092, which is aDivisional of application Ser. No. 10/952,780 filed on Sep. 30, 2004,now U.S. Pat. No. 7,265,808, which is a Divisional of application Ser.No. 10/029,967, filed on Dec. 31, 2001, now U.S. Pat. No. 6,809,791, andfor which priority is claimed under 35 U.S.C. §120; and this applicationclaims the benefit of Korean Patent Applications No. 2001-4937, filed onFeb. 1, 2001, and No. 2001-5044, filed on Feb. 2, 2001, under 35 U.S.C.§119. The entirety of each of these applications is hereby incorporatedby reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a liquid crystal display device, andmore particularly to a transflective liquid crystal display device.

2. Description of Related Art

Recently, liquid crystal display (LCD) devices with light, thin, and lowpower consumption characteristics are used in office automationequipment and video units and the like. Such LCDs typically use a liquidcrystal (LC) interposed between upper and lower substrates with anoptical anisotropy. Since the LC has thin and long LC molecules, thealignment direction of the LC molecules can be controlled by applying anelectric field to the LC molecules. When the alignment direction of theLC molecules is properly adjusted, the LC is aligned and light isrefracted along the alignment direction of the LC molecules to displayimages.

In general, LCD devices are divided into transmissive LCD devices andreflective LCD devices according to whether the display device uses aninternal or external light source.

A conventional transmissive LCD device includes an LCD panel and abacklight device. The incident light from the backlight is attenuatedduring the transmission so that the actual transmittance is only about7%. The transmissive LCD device requires a high, initial brightness, andthus electrical power consumption by the backlight device increases. Arelatively heavy battery is needed to supply a sufficient power to thebacklight of such a device, and the battery can not be used for alengthy period of time.

In order to overcome the problems described above, the reflective LCDhas been developed. Since the reflective LCD device uses ambient lightinstead of the backlight by using a reflective opaque material as apixel electrode, it is light and easy to carry. In addition, the powerconsumption of the reflective LCD device is reduced so that thereflective LCD device can be used as an electric diary or a PDA(personal digital assistant).

However, the reflective LCD device is affected by its surroundings. Forexample, the brightness of ambient light in an office differs largelyfrom that of the outdoors. Therefore, the reflective LCD device can notbe used where the ambient light is weak or does not exist. In order toovercome the problems described above, a transflective LCD device hasbeen researched and developed. The transflective LCD device can betransferred according to the user's selection from the transmissive modeto the reflective mode, or vise versa.

FIG. 1 is a schematic perspective view of a conventional transflectiveLCD device 11.

In FIG. 1, the conventional transflective LCD device 11 includes upperand lower substrates 15 and 21 with an interposed liquid crystal 23. Theupper and lower substrates 15 and 21 are sometimes respectively referredto as a color filter substrate and an array substrate. On a surfacefacing the lower substrate 21, the upper substrate 15 includes a blackmatrix 16 and a color filter layer 18. The color filter layer 18includes a matrix array of sub-color fiters 17 of red (R), green (G),and blue (B) that are formed such that each color filter is bordered bythe black matrix 16. The upper substrate 15 also includes a commonelectrode 13 over the color filter layer 18 and over the black matrix16. On a surface facing the upper substrate 15, the lower substrate 21includes an array of thin film transistors (TFTs) “T” that act asswitching devices. The array of TFTs is formed to correspond with thematrix of color filters. A plurality of crossing gate and data lines 25and 27 are positioned such that a TFT is located near each crossing ofthe gate and data lines 25 and 27. The lower substrate 21 also includesa plurality of pixel electrodes 19, each in an area defined between thegate and data lines 25 and 27. Such areas are often referred to as pixelregions “P.” Each pixel electrode 19 includes a transmissive portion “A”and a reflective portion “C”. The transmissive portion “A” is usuallyformed from a transparent conductive material having a good lighttransmittance, for example, indium-tin-oxide (ITO). Moreover, aconductive metallic material having a superior light reflectivity isused for the reflective portion “C”.

FIG. 2 is a schematic cross-sectional view of a conventionaltransflective LCD device such as the device 11 of FIG. 1.

In FIG. 2, upper and lower substrates 15 and 21 are facing and spacedapart from each other and a liquid crystal layer 23 is interposedtherebetween. A backlight apparatus 45 is disposed over the outersurface of the lower substrate 21. On the inner side of the uppersubstrate 15, a color filter layer 18 for passing only the light of aspecific wavelength and a common electrode 14 functioning as oneelectrode for applying a voltage to the liquid crystal layer 23 aresubsequently formed. On the inner surface of the lower substrate 21, apixel electrode 32 functioning as the other electrode for applying avoltage to the liquid crystal layer 23, a passivation layer 34 having atransmissive hole 31 exposing a portion of the pixel electrode 32, and areflective plate 36 are subsequently formed. An area corresponding tothe reflective plate 36 is a reflective portion “C” and an areacorresponding to the portion of the pixel electrode 32 exposed by thetransmissive hole 31 is a transmissive portion “A”.

A cell gap “d₁” at the transmissive portion “A” is about twice of a cellgap “d₂” at the reflective portion “C” to reduce the light pathdifference. A retardation “Δn·d” of the liquid crystal layer 23 isdefined by a multiplication of refractive index anisotropy “Δn” with acell gap “d” and the light efficiency of the LCD device is proportionalto the retardation. Therefore, to reduce the difference of lightefficiencies between the reflective and transmissive modes, theretardations of the liquid crystal layer 23 at two portions should benearly equal to each other by making the cell gap of the transmissiveportion larger than that of the reflective portion.

However, even though the light efficiencies of the liquid crystal layerbetween the reflective and transmissive modes become equal by making thecell gaps different, the light passing the color filters at differentlocations is different so that the brightness can be different at thefront of the display device. The transmittance of the color filter resinwhose absorption coefficient is high for a specific wavelength and lowfor the other wavelengths has the following relation considering onlythe absorption, i.e., the transmittance is inversely proportional to theabsorption coefficient and the distance that light passes:T=exp(−α(λ)d)where T is transmittance, α(λ) is an absorption coefficient depending onthe wavelength and d is a distance that light passes.

Since the color filter resin is a viscous material, the thickness of thecolor filter resin is hard to control and the color filter layer can notbe made less than a specific thickness. Therefore, the color filterlayers of the reflective and transmissive portions have the samethickness and the different absorption coefficient (i.e., differentmaterial) for the uniform transmittance.

However, if the color filter layers of the reflective and transmissiveportions are formed of different materials, the process and the costwould be increased and the yield would be decreased.

To solve the above problems, a fabricating method of the color filterlayers with the same resin is suggested. In this method, the colorfilter layers at the reflective and transmissive portions have the sameabsorption coefficient but a different thickness so that thetransmittance has the same value.

FIGS. 3A and 3B are transmittance spectrums of first and second redcolor filter layers for the reflective mode having a specific thicknessand two times the specific thickness, respectively.

Generally, a visible light has a wavelength ranging about 400 to 700nanometers. Red (R), green (G) and blue (B) colors roughly correspond towavelengths of 650, 550 and 450 nanometers, respectively.

In FIG. 3A, the transmittances at wavelengths corresponding to R, G andB are about 97%, 20% and 58%, respectively. Even though thetransmittance for red color is high, the transmittances for the othercolors are also not negligible so that a satisfying color purity is notobtained.

In FIG. 3B, since the second red color filter layer has twice thethickness and square transmittance compared with the first red colorfilter layer of FIG. 2A, the transmittances at wavelengths correspondingto R, G and B are about 94%, 4% and 34%, respectively. Although thetransmittance is decreased for all colors, the decreased amount isdifferent for the individual colors, for example, about 5%, 16% and 24%for R, G and B, respectively.

Therefore, the color purity of the second red color filter layer isimproved and this result can be applied for the green and blue colorfilters so that the transmittance and color purity of the transflectiveLCD device using the same kind of color filter resin can be uniform forthe reflective and transmissive portions.

A transflective LCD device using a dual thickness color filter (DCF) ofthe above-mentioned principle is suggested in Korean Patent ApplicationNo. 2001-9979 of the applicant.

FIG. 4 is a cross-sectional view of a transflective LCD device using theDCF according to a related art.

In FIG. 4, a transparent buffer layer 64 is formed on the inner surfaceof the upper substrate 15 only at a reflective portion “C”, and a colorfilter layer 62 is formed on the entire upper substrate 15. Therefore,the color filter layer 62 of a transmissive portion “A” is thicker thanthat of the reflective portion “C” so that the color purity of thetransmissive portion “A” can be improved. The transparent buffer layer64 is formed by depositing and patterning one of an insulating materialgroup comprising acrylic resin, benzocyclobutene (BCB) and siliconnitride (SiNx). Therefore, the buffer layer 64 of a yellowish color isnot perfectly transparent and the transmittance of the buffer layer 64is lower than that of glass substrate. Moreover, since light ispartially reflected at the interface between the buffer layer 64 and thesubstrate 15, the transmittance at the reflective portion “C” is moredecreased.

FIGS. 5A and 5B are cross-sectional views of color filter substratesusing the DCF having transparent buffer layers of first and secondthicknesses, respectively, according to a related art.

In FIG. 5A, the substrate 15 has a transmissive portion “A” and areflective portion “C”. A black matrix 70 and a transparent buffer layer64 are formed in the reflective portion “C” and a color filter layer 62is formed on the entire surface of the substrate 15. Since thetransparent buffer layer 64 of a first thickness has a low step 52 atthe borderline of the transmissive portion “A” and the reflectiveportion “C” so that the surface of the color filter layer 62 can beplanarized. Moreover, since the color filter layer 62 at thetransmissive portion “A” is thicker than that at the reflective portion“C”, the color purity can be improved at the transmissive portion “A”.However, since the thickness of the transparent buffer layer 64 has alimit for the planarization of the color filter layer 62, the thicknessratio of the color filter layer 62 also has a limit and the improvementof the color purity is limited.

In FIG. 5B, to have a desired thickness ratio of the color filter layer62, the transparent buffer layer 64 has a second thickness higher thanthe first thickness of FIG. 5A and a high step 54 at the borderline ofthe transmissive portion “A” and the reflective portion “C”. Since thecolor filter layer 64 is made of a viscous resin and formed according tothe surface of the underlayer, the color filter layer 64 also has a step55 at the top surface. Therefore, the difference “Δd” between thedesigned thickness d₃ and the fabricated thickness d₄ occurs and theimprovement of the color purity of the transmissive portion “A” islimited.

Generally, the thickness of a conventional color filter layer for thereflective LCD device is controlled to have the average transmittance inthe range of about 55 to 70%. If the thickness of the color filter layeris increased, the transmittance and the color appearance of the colorfilter layer are varied. For the color filter layer twice as thick asthe conventional color filter, the transmittance and the colorappearance are 46% and 24.9%, respectively. On the other hand, for thecolor filter layer 1.3 times as thick as the conventional color filter,the transmittance and the color appearance are 54.7% and 14.1%,respectively. Consequently, if the color filter layer of thetransmissive portion is not formed with a desired thickness, the colorproperty of the transmissive portion can not approach that of thereflective portion.

Furthermore, since the step of the color filter layer also degrades theplanarization property of the common electrode on the color filterlayer, the display quality of conventional LCDs is degraded.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a reflective liquidcrystal display device that substantially obviates one or more of theproblems due to limitations and disadvantages of the related art.

An object of the present invention is to provide a color filtersubstrate of a reflective liquid crystal display device that has a hightransmittance and color purity, and a manufacturing method of the colorfilter substrate.

Another object of the present invention is to provide a color filtersubstrate of a reflective liquid crystal display device that has a highcolor purity, and a manufacturing method of the color filter substrate.

Additional features and advantages of the invention will be set forth inthe description which follows, and in part will be apparent from thedescription, or may be learned by practice of the invention. Theobjectives and other advantages of the invention will be realized andattained by the structure particularly pointed out in the writtendescription and claims hereof as well as the appended drawings.

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described, a colorfilter substrate for a liquid crystal display device according to anembodiment of the present invention includes: a substrate having atransmissive portion and a reflective portion, the transmissive portionhaving a groove; a black matrix on the substrate; and a color filterlayer on the black matrix and on the substrate.

In another aspect, a method of fabricating a color filter substrate fora liquid crystal display device includes: forming a groove on asubstrate, the substrate having a transmissive portion and a reflectiveportion, the transmissive portion having the groove; forming a blackmatrix on the substrate; and forming a color filter layer of a firstcolor on the black matrix and the substrate.

In another aspect, a color filter substrate for a liquid crystal displaydevice includes: a substrate having a transmissive portion and areflective portion; a black matrix on the substrate; a plurality ofbuffer patterns at the reflective portion, the plurality of bufferpatterns having a substantially uneven shape; and a color filter layerat the transmissive and reflective portions.

In another aspect, a method of fabricating a color filter substrate fora liquid crystal display device includes: forming a black matrix on asubstrate, the substrate having a transmissive portion and a reflectiveportion; forming a plurality of buffer patterns at the transmissiveportion, the plurality of buffer patterns having a substantially unevenshape; and forming a color filter layer at the transmissive andreflective portions.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description given hereinbelow and the accompanying drawingswhich are given by way of illustration only, and thus do not limit thepresent invention.

In the drawings:

FIG. 1 is a schematic perspective view of a conventional transflectiveLCD device;

FIG. 2 is a schematic cross-sectional view of a conventionaltransflective LCD device;

FIGS. 3A and 3B are transmittance spectrums of first and second redcolor filter layers for the reflective mode having a specific thicknessand twice of the specific thickness, respectively, according to arelated art;

FIG. 4 is a cross-sectional view of a transflective LCD device usingDCF;

FIGS. 5A and 5B are cross-sectional views of color filter substratesusing DCF having transparent buffer layers of first and secondthicknesses, respectively, according to a related art;

FIGS. 6A to 6C are schematic cross-sectional views of a color filtersubstrate illustrating a fabricating process according to a firstembodiment of the present invention;

FIG. 7 is a schematic cross-sectional view of a color filter substrateaccording to a second embodiment of the present invention;

FIGS. 8A to 8C are schematic cross-sectional views of a color filtersubstrate illustrating a fabricating process according to a thirdembodiment of the present invention;

FIG. 9 is a schematic cross-sectional view of a color filter substrateaccording to a fourth embodiment of the present invention;

FIGS. 10A to 10D are schematic cross-sectional views of a color filtersubstrate illustrating a fabricating process according to a fifthembodiment of the present invention;

FIG. 11 is a schematic cross-sectional view of a color filter substrateillustrating the principle of the present invention;

FIGS. 12A to 12F are schematic plan views of a plurality of bufferpatterns according to several embodiments of the present invention;

FIGS. 13A to 13C are schematic cross-sectional views of a color filtersubstrate illustrating a fabricating process according to a sixthembodiment of the present invention;

FIG. 14 is a schematic cross-sectional view of a color filter substrateaccording to a seventh embodiment of the present invention;

FIGS. 15A to 15D are schematic cross-sectional views of a color filtersubstrate illustrating a fabricating process according to an eighthembodiment of the present invention; and

FIG. 16 is a cross-sectional view of a color filter substrate accordingto a ninth embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Reference will now be made in detail to the preferred embodiments of thepresent invention, example of which is illustrated in the accompanyingdrawing.

FIGS. 6A to 6C are schematic cross-sectional views of a color filtersubstrate illustrating a fabricating process thereof according to afirst embodiment of the present invention. The color filter substrate isusable in any type of an LCD device or other display device. In FIGS. 6Ato 6C, the substrate 112 has a transmissive portion “A” and a reflectiveportion “C”.

In FIG. 6A, a groove 114 is formed at the transmissive portion “A” ofthe LCD device by photolithography and etching processes, or othertechniques. The depth d₅ from the top surface of an upper substrate 112is determined considering the thickness ratio of the color filter layerbetween the transmissive and reflective portions “A” and “C”.Preferably, this thickness ratio may be 1:2.

In FIG. 6B, a black matrix 116 is formed on the substrate 112 bydepositing and patterning a black resin or an opaque metallic material.

In FIG. 6C, a color filter layer 118 of a first color is formed over thesubstrate 112 and a portion of the black matrix 116 by depositing andpatterning a color resin. By repeating this process for second and thirdcolors, a color filter layer of three colors can be selectively formedon the substrate 112. The step height “Δd” of the color filter layer 118is within a range of about 0.1 to a few micrometers.

FIG. 7 a schematic cross-sectional view of a color filter substrateaccording to a second embodiment of the present invention.

In FIG. 7, the color filter substrate is identical to that in the firstembodiment, except that a black matrix 116 is formed on a color filterlayer 118 and the dimensions of the color filter substrate may vary asneeded.

In the case of a transparent plastic substrate, a groove can be formedby a molding process during a fabricating process of the substrate andthe molding process is more suitable to the control of the depth thanthe etching process.

FIGS. 8A to 8C are schematic cross-sectional views of a color filtersubstrate for an LCD device illustrating a fabricating process thereofaccording to a third embodiment of the present invention.

In FIG. 8A, a substrate 120 is made of transparent plastic so that agroove 114 can be formed at a transmissive portion of the LCD by amolding process during a fabricating process of the substrate 120. Theuse of a transparent plastic material allows an easy control over theprofile of the groove 114.

In FIG. 8B, a black matrix 116 is then formed selectively on thesubstrate 112 by depositing and patterning a black resin, an opaquemetallic material, or the like.

In FIG. 8C, a color filter layer 118 of a first color is formed on thesubstrate 120 and portions of the black matrix 116 by depositing andpatterning a color resin. By repeating this process for second and thirdcolors, a color filter layer of three colors can be selectively formedon the substrate 120. This completes the process of forming the colorfilter substrate according to this embodiment.

FIG. 9 is a schematic cross-sectional view of a color filter substratefor an LCD device according to a fourth embodiment of the presentinvention.

In FIG. 9, the color filter substrate is identical to that of the thirdembodiment, except that a black matrix 116 is formed on a color filterlayer 118 and the dimensions of the color filter substrate may vary asneeded.

FIGS. 10A to 10D are schematic cross-sectional views except that of acolor filter substrate for an LCD device illustrating a fabricatingprocess thereof according to a fifth embodiment of the presentinvention. In this embodiment as shown FIGS. 10A to 10D, the substrate112 has a transmissive portion “A” and a reflective portion “C”.

In FIG. 10A, after depositing an opaque metallic material on thesubstrate 112, an opaque metal pattern 115 is formed by selectivelyremoving the deposited opaque metallic material in the transmissiveportion “A”.

In FIG. 10B, a groove 114 is then formed at the transmissive portion “A”by selectively etching the substrate 112 in the transmissive portion “A”as the opaque metal pattern 115 is used as a mask for this etchingprocess.

In FIG. 10C, a black matrix 116 is then formed by selectively etchingthe opaque metal pattern 115.

In FIG. 10D, a color filter layer 118 of a first color is formed bydepositing and patterning a color resin on the substrate 112 and theblack matrix 116. By repeating this process for second and third colors,a color filter layer of three colors can be formed selectively on thesubstrate 112.

In the first to fifth embodiments, since the groove of the transmissiveportion is formed by etching the substrate itself, a separate bufferlayer is not necessary and thus, the production cost of the color filtersubstrate can be reduced. If the substrate of transparent plastic isused, the etching process for the groove is also unnecessary due to themolding process, which further reduces the production cost. Moreover,since the buffer layer is not used, the substrate of the reflectiveportion does not have an interface between the buffer layer and thesubstrate so that the reflection from the interface can not occur andthe device performance is improved.

However, since the color filter layer has a step at its top surface, thethickness ratio of the color filter layer between the transmissive andreflective portions has a limit so that the improvement of colorproperty can be somewhat limited. Therefore, a method is provided in thepresent invention for obtaining a desired thickness ratio and minimizingthe step at the top surface of the color filter layer. This methodemploys a plurality of buffer patterns as discussed below.

FIG. 11 is a schematic cross-sectional view of a color filter substrateillustrating the principle of the present invention.

In FIG. 11, a substrate 112 has a transmissive portion “A” and areflective portion “C” and a plurality of buffer patterns 117 having asubstantially uneven shape are formed at the reflective portion “C”. Theshape of the buffer patterns 117 can be any shape. Since the pluralityof buffer patterns 117 have a lot of fine grooves, the thickness “d₆” ofcolor filter layer of the reflective portion “C” can be reduced orminimized so that the thickness ratio (d₆:d₇) of the color filter layerbetween the transmissive and reflective portions “A” and “C” can beincreased. Therefore, the color difference between the transmissive andreflective portions “A” and “C” can be further reduced.

FIGS. 12A to 12F are schematic top plan views of a plurality of bufferpatterns usable in a color filter substrate according to severalembodiments of the present invention. In FIGS. 12A to 12F, a hatchedregion means an etched region, i.e., a concave region and a white regionmeans a buffer pattern, i.e., a convex region.

As shown in FIGS. 12A and 12B, a buffer pattern having a plurality ofcircular concave holes 124, and a plurality of circular convex bufferpatterns 125 are provided.

In FIGS. 12C and 12D, a buffer pattern having a plurality of concaveholes 126 and convex buffer patterns 127 have a rectangular shape.

In FIGS. 12E and 12F, a plurality of buffer patterns 128 and 129 areformed along the direction of columns and rows, respectively.

FIGS. 13A to 13C are schematic cross-sectional views of a color filtersubstrate illustrating a fabricating process thereof according to asixth embodiment of the present invention.

In FIG. 13A, a black matrix 116 is formed on a substrate 112. The blackmatrix 116 has a structure of a single layer of chromium (Cr) or adouble layer of chromium (Cr) and chromium oxide (CrOx).

In FIG. 13B, a plurality of buffer patterns 117 covering the blackmatrix 116 are formed only at the reflective portion “C” by depositingand etching a transparent material such as benzocyclobutene (BCB),acrylic resin, or silicon nitride (SiNx). The plurality of bufferpatterns 117 have a substantially uneven shape, e.g., fine grooves 142between projections.

In FIG. 13C, a color filter layer 118 is formed on the plurality ofbuffer patterns 117. Even though the color filter layer 118 is notplanarized, a reduced step 155 is produced due to the fine grooves 142between the plurality of buffer patterns. Here, the height “d₈” of thebottom of the grooves 142 equals the height “d₉” of the surface of thesubstrate 112 at the transmissive portion “A”. By repeating this processfor three color filters, a full color filter layer of three colors canbe formed.

FIG. 14 is a schematic cross-sectional view of a color filter substrateaccording to a seventh embodiment of the present invention.

In FIG. 14, the color filter substrate is identical to that shown inFIG. 13C, except that the height “d₁₀” from the bottom surface ofgrooves 144 to the bottom surface of the substrate 112 is larger thanthe height “d₁₁” of the substrate 112 at the transmissive portion “A”.In this structure, since the plurality of buffer patterns 117 can belowered, a surface step 156 of the color filter layer 118 can be furtherreduced.

FIGS. 15A to 15D are schematic cross-sectional views of a color filtersubstrate illustrating a fabricating process thereof according to aneighth embodiment of the present invention.

As shown in FIG. 15A, in this embodiment of the color filter substrate,a substrate 200 has a transmissive portion “A” and a reflective portion“C”. An opaque metal pattern 204 is formed selectively on the substrate200 only at the reflective portion “C”.

In FIG. 15B, a plurality of buffer patterns 206 are formed byselectively etching the substrate 200 while the opaque metal pattern 204is used as a mask. In this etching process, the substrate 200 under theopaque metal pattern 204 is not etched to become a convex portion of theplurality of buffer patterns 206. Also, a portion of the substrate 200in the transmissive portion “A” is removed to provide a groove 250.

In FIG. 15C, a black matrix 208 is then formed by further etching theopaque metal pattern 204.

In FIG. 15D, a color filter layer 210 is formed over the substrate 200.Even though the color filter layer 210 has a surface step 255 betweenthe transmissive and reflective portions “A” and “C”, the surface step255 is reduced due to the plurality of buffer patterns 206.

FIG. 16 is a cross-sectional view of a color filter substrate accordingto a ninth embodiment of the present invention.

As shown in FIG. 16, the color filter substrate is identical to thatshown in FIG. 150, except that the height “d₁₂” from the bottom surfaceof the plurality of buffer patterns 206 to the bottom surface of thesubstrate 200 is bigger than the height “d₁₃” of the substrate 200 atthe transmissive portion “A”. The ninth embodiment can be acquired byadding an etching process for the transmissive portion “A” to theprocess of the eighth embodiment shown in FIGS. 15A to 15D. In the ninthembodiment structure, since the plurality of buffer patterns 206 can belowered, a surface step 256 of the color filter layer 210 is furtherreduced so that the color purity of the display device can be furtherimproved.

The plurality of buffer patterns according to the embodiments of thepresent invention can have a uniform pitch in the range of about 14 to45 micrometers.

The present invention is not limited to LCD devices, but is applicableto other types of display devices and apparatuses.

It will be apparent to those skilled in the art that variousmodifications and variation can be made in the method of manufacturing aflat pane display device of the present invention without departing fromthe spirit or scope of the invention. Thus, it is intended that thepresent invention cover the modifications and variations of thisinvention provided they come within the scope of the appended claims andtheir equivalents.

1. A color filter substrate for a liquid crystal display device,comprising: a base substrate having a plurality of first regions and aplurality of second regions; a black matrix on the base substrate; aplurality of buffer patterns at each of the plurality of second regionsexcept the first regions, one of the plurality of buffer patternscovering an entire of one of the second regions and having concaveportions at the one of the second regions; and a color filter layer atthe first and second regions.
 2. The color filter substrate according toclaim 1, wherein the plurality of buffer patterns are formed byselectively removing the base substrate.
 3. The color filter substrateaccording to claim 2, wherein the base substrate is made of glass. 4.The color filter substrate according to claim 1, wherein the pluralityof buffer patterns are formed by depositing and selectively removing atransparent material.
 5. The color filter substrate according to claim4, wherein the plurality of buffer patterns are formed of one ofbenzocyclobutene, acrylic resin and silicon nitride.
 6. The color filtersubstrate according to claim 1, wherein the plurality of buffer patternshave a uniform pitch.
 7. The color filter substrate according to claim6, wherein the pitch is within a range of about 14 to 45 micrometers. 8.The color filter substrate according to claim 1, wherein a bottomsurface of the plurality of the buffer patterns is located higher than atop surface of the first region of the base substrate.
 9. A color filtersubstrate for a liquid crystal display device, comprising: a basesubstrate having a plurality of first regions and a plurality of secondregions; a black matrix on the base substrate; a plurality of bufferpatterns at each of the plurality of second regions, one of theplurality of buffer patterns covering an entire of one of the secondregions and having concave portions at the one of the second regions;and a color filter layer at the first and second regions, wherein thecolor filter at the first region is thicker than that at the secondregion.